In many spray applications, such as humidification or evaporative cooling, it is desirable to generate relatively fine spray particles so as to maximize surface area for distribution in the atmosphere. For this purpose, it is known to use air assisted spray nozzle assemblies in which a pressurized gas such as air is used to break down or atomize a liquid flow stream into very fine liquid particles. For example, in some air assisted nozzle assemblies the liquid is mechanically broken down primarily in an atomizing chamber located in the nozzle assembly upstream from a spray tip or air cap which serves to form the discharging spray pattern. Alternatively, the liquid particle break down can occur in the air cap itself.
From an efficiency and economic operating standpoint it is desirable that such particle breakdown be effected using relatively low air flow rate and pressure. Heretofore this has created problems. In particular, spray tips or air caps which provide efficient and economic operation are generally relatively complex in design, and hence relatively expensive to produce. Moreover, even when extremely fine spray particles are generated and discharged, it can be difficult to direct those particles with the desired control, such as in well defined, relatively wide flat spray patterns.